1. Field
The present disclosure relates to a nonaqueous electrolyte for a lithium secondary battery and a lithium secondary battery employing the same.
2. Description of the Related Art
Recently, lithium secondary batteries have drawn significant attention as power sources for small portable electronic devices. Lithium batteries using a nonaqueous electrolyte have high energy density by exhibiting a discharge voltage that is about twice or higher than that of batteries using an aqueous alkali electrolyte.
In lithium secondary batteries, lithium-transition metal oxides, such as LiCoO2, LiMn2O4, or LiNi1-xCoxO2 (wherein 0<x<1), which have a structure that allows intercalation of lithium ions, are mainly used as positive active materials.
In lithium secondary batteries, various forms of carbonaceous materials, including artificial graphite, natural graphite, hard carbon, silicon, or a combination thereof, which allow intercalation and deintercalation of lithium ions, have been used as negative active materials.
As for a nonaqueous electrolyte in a lithium secondary battery, a lithium salt dissolved in an organic solvent may be used. As for the lithium salt, a fluorine-containing lithium salt may be used. The fluorine-containing lithium salt may decompose and generate hydrogen fluoride (HF) while operating a lithium secondary battery. There is a problem that the generated HF may decompose a solid electrolyte interface (SEI) layer formed at an interface between a negative electrode and a nonaqueous electrolyte and elute metal ions from a positive electrode, thereby deteriorating battery performance. Thus, there remains a need for an improved electrolyte.